Tank bottoms equipped with improved means for testing seams and recovering leakage from same



Jan. 25, 1949.

. J. H. WlGGlNS A 2,460,054 TANK BOTTOMS EQUIPPED wma IMPROVED MEANS FOR TESTING SEAMS AND RECOVERING I LEAKAGE FROM SAME Original Filed June 7, 1943 5 Sheets-Sheet l 1 ATTORNEY W T m w I Jan. 25, 1949. J. HSWIGGINS TANK BOTTOMS EQUIPPED WITH IMPROVED MEANS FOR TESTING SEAMS AND RECOVERING LEAKAGE FROM SAME 3 Sheets-Sheet 3 Original Filed June 7, 1943 INVENTOR; JOHN H. W/GGINS TTORNEY Patented Jan. 25, 1949 UNITED STATES PATENT ()FFI CE 2,460,054 TANK. BOTTOMS: EQUIBPEB WITH 11.-

PROVED MEANS FOR 'EESTING SEAMS AND EECOVEEING- LEAKAGE FROM SAME John. H.- Wiggins, Chicago, IlI'. Continuation. of application. Serial No.. 490,119,

rum 1,, 19.43-

This. app

1945, Serial No; 6301933 I. Clainn (01. 2213-75) This invention relates to tanks and containers of the kind that comprise a bottom made up'of metal plates joined together by bolts; rivets or Welding, mypresent application being a continuation of mypendin-g application Serial No. 490,119, filed June 7",, 1943', nowabandoned.

In tanks of large size (often inexcess of 100' ft. in diameter), the entire or major portion of the area of the tank bottom. rests directly on the ground, and consequently, if a leak develops in the bottom of a storage tank of conventional construction while. the tankis in service or' filled- With liquid, it is impossible to recover the leakage or even detect or approximately locate the defective scam in the tank bottom that has become leaky; Also in tank'bottoms'of conventional construction, there is no reliable or easy wayof testing the scams or joints between the tank bottom plates, during the operation of connecting or" joining saidplates togethen The result is that tremendous amounts of oil and gasoline are lost annually through leaks in the bottoms of storage tanks; In many instances; the leakage orseepage through defective seams of tank bottoms is soexcessive, that: it is considered sound practice to drillwells in ground that has become saturated with oil or" gasoline that has escaped through defective-joints the-bottoms of storage" tanks over aperiod ofyears; so as to -recover the oil or gasoline that has seeped throughthe ground to the first stratum of ground water; and} thereafter, separate the oil fromout of the ground.

Myinvention has: for one of its. objectsto provide a storage. tank, equipped: with a. bottom constructed. of metal plates that are joined together while they are disposed inthe position, or the approximate. position, they occupy in the. finished structure, and which. have. combined with. same troughs. or trough; spaces: that are adaptedto recover leakage; or seepage from defective seams. of the: bottom, and: also adapted. to receive. a medium. that. is applied toor exerted on the seams of. the tank bottom. to test or treat: said seams.

Another object. is: ta provide a. metal tank bottom. of novel. construction,. that; can bequickly and reliably tested for leaks; either" at: the time of construction, or while the tank is in use,

Anotherobject is to: provide a tank having an upright side walll and a bottom that is: built; on the ground and equipped with: troughs that will: trapand convey to inspection or; collection points located cm the exterior of the tankat theperiphery of the bottom. leakage thatlescapesthe mixture pumped li'cation. November. 26

2 through a defective joint or joints in the bottom of the tank; and

Still another object of my invention is to provide-"atank bottom that is easy to build, and

of sue-h design or construction that if any of the seams'orjoints of same are defective, the defects can be easily located.

Figure I of the drawings is a top plan view of a tank bottom: constructed in accordance with my invention.

View, taken on the line 3-3' of Figure I.

Figured is an enlarged, fragmentary side elevational View of the tank, as viewed from the left hand side of Figure I}.

Figure 5 is an enlarged'fragmentary top plan View of the tank bottom,v shown in Figure 1, illustrating the lapped tank bottom plates and the interconnected troughs on the; underside of same.

Figure 6' isavertical sectional view, taken on the line 56 of Figure 5.

Figure '7 is a vertical sectional View, taken on the line i -I of Figure 5.

Figure 8 is a sectional view, illustrating my invention employed in a tank bottom composed of lapwelded plates: and

Figure 9 is a sectional View, taken 99 of Figure 8', looking in the: direction indicated bythearrows.

Brieflydescribed, my improved tank bottom consists of metal plates joined together by bolts, rivets or welding, and provided with a series of interconnected troughs that are adapted to trap and convey to one or more inspection points or one or more collecting receptacles, any substanceor material that escapes from the tank through a leaky joint! or joints in the bottom of the tank,

said: troughsalso being adapted. to. be used as flow conduits for; a. medium. employed to test. said joints or to locate: a leak in same, or used as suction conduits, in which a. minus pressure can be. created; either for the purpose; of testing the joints: for leaks, or to. cause'a sealing compound: on'. the top; side ofthe tank bottom to. be drawn intothe scams: or joints: of said bottonL. The particular construction of said' troughs and the way: in; which they are combined; with the tank bottom; are immaterial; so: far as my broad idea is: concerned. Pneferably, they. are built into the tank bottom; or: combined. with: same dining the operation of joining; or connecting together the metal? plates that-constitute the tank bottom, and

on the line they are of such construction or design that during the operation of building the bottom, and subsequently, testing the seams or joints of same, the tank bottom plates rest on the ground, or occupy the same position, or approximately the same position, they assume in the finished structure. As hereinafter 'explained the troughs may consist of prefabricated members, preferably of substantially channel shape in cross section, disposed with the top edges of their side legs in contact with the underside of the tank bottom,

two parallel, spaced strips 2 of compressible or resilient material that constitute the side walls or side portions'of the trough, said built-up structure being fastened to the tank bottom by bolts 3 that project upwardly through the bottom plate I of the trough, and through a lapped seam of the tank bottom, as shown in Figure 6. The nuts 3 of said bolts are of the can type, or, in other or they may be formed fromhorizontal, or substantially horizontally-disposed, plates arranged in spaced relation with the underside of the tank bottom and sealed to same by resilient elements that constitute the side walls or side portions of the troughs. structed of lapped plates, the troughs are preferably arranged so that the seams of the tank bottom are disposed over approximately the centers of the troughs. The' troughs under the various seams or joints in the tank bottom are preferably connected with each other, so as to form a continuous or completely interconnected system, and in order to simplify the operation of producing tight joints between the troughs and the underside of the tank bottom, the troughs are so disposed with relation to the seams of said bottom, that the'side portions of the troughs .do not cross the laps of said seams. The troughs can slope either towards the center of the tank bottom, or towards the peripheral edge of said bottom, depending, of course, upon the grade or slope of the tank bottom. In instances where the tank bottomslopes down wardly from its center towards its peripheral edge, the trough system preferably comprises a plurality of inspection points located at the peripheral edge of the tank bottom, in spaced relation around the circumference thereby making it possible to determine, within fairly close limits, the approximate location of a leak in the tank bottom. In the case of a tank bottom that slopes from its peripheral edge towards its center, the trough system will comprise a center discharge pipe buried in the ground and provided with a lateral branch that leads to an inspection point located at the peripheral edge of the tank bottom. In addition to the inspec tion point or points above referred to, the trough system may comprise one or more collection receptacles, into which the troughs discharge the substance or material that has leaked through a joint or joints of the tank bottom.

In Figures 1 to 7, inclusive, of the drawings,

I have illustrated my invention applied to a tank provided with a bottom composed of metal plates portions joined together by suitable fastening devices 1;, and

at having lapped edge bolts or other made gas and liquid-tight by cement or other suitable sealing compound 2 applied to the edges of said plateson the top side of the tank bottom.

In the case of a tank bottom con of same, a

the'centers of the laps'of' side of. the tank bottom.

words, have closed ends, and they are arranged on the topside of the tank bottom. When said nuts are tightened, the bottom plate I will be drawn upwardly towards thetank bottom, and the compressible or resilient strips 2 that form the side wall portions of the trough will be deformed from the shape shown in broken lines in Figure 6, to the shape shown in full lines in said figure, thereby sealing the side portions of the trough to the bottom plate I and to the under- I have found that sponge or synthetic rubber is a suitable material from which to form the strips 2, and preferably, synthetic rubber cement is applied to the top edges of said strips before they are interposed between the plates x of the tank bottom and the bottom plate l of the trough. Spacing devices 4-,

formed preferably by metal washers, are arranged V of the construction above described are inexpensive and easy-to construct, they willremain in a gas and liquid-tight condition, and they will not freeze and break if filled with water, due to the fact that they have resilient side walls,

i The tank is preferably provided with a plurality of inspection stations, or inspection points, located in spaced relation around the peripheral edge of the tank bottom, and formed preferably by short drain pipes 5 provided with shut-off valves Ea; as shown in Figures 2 and 3. If, after the tank has been placed in service, enough leaks develop in the tank bottom to make it worth while to collect the substance or material escaping f1 cm the tank, a collecting receptacle or receptacles I can be connected to one or more of the drain pipes 5, as shown in Figure 2. The tank is also preferably provided with means for enabling a testingmedium to be supplied to-the troughs and appliedto the seamsor joints of the tank bottom,

' for the. purpose of testing said joints for leaks or On the underside of said tank bottom there is a series of interconnected troughs located directly beneath the seams or joints in said bottom, as shown in broken lines in Figure 1, and designated by the referencecharacter A. Said troughs are substantially channel-shaped in cross section, and they are secured to the tank bottom with the top edges of the side portions of said troughs sealed to the underside of the tank bottom. One con- 5 venient and inexpensive way of building said troughs, is to construct each trough or each trough section, from a horizontally-disposed bottom plate I, to the top side of which is'attached to facilitate the application of a sealing substance to said joints.v 'In the formiof my invention herein illustrated, the meansjust referred to includes an elevated reservoir 8 on the exterior of the tank adapted to hold the testing medium and concontrolleddrain pipes;5 of the trough system, as shown-in Figure 2, avent pipe 9 communicating with the highest point of the trough system, and

provided with a-control valve 9 and an overflow reservoir H3 at the upper endof the vent pipe 9.

As shown in Figures 1, 2, 3 and 4 of the drawings,; the. ducts 5 which lead from the troughs to the inspection. stations on tank-project downwardly from thebottom of the troughs and extend laterally underneath the side wall of. the tank. ;;It will also be noted that in a structureofgthe kind shown in Figure 2, any

liquid thatgexists in or collects ,in the trough system will flow by gravity to a point or points on the exterior ofithe tankywhere is can easily be inspected or recovered;

the :exteriorof the 'constructlngftlie t set-mm, the mammplatesl of the. troughs... with. the resilient strips; 2 posi ioned thereonaarerlaict ontha ground be}.

- neath the lapped. plates. rwhich. constitute. the

bottom of the. tank, and: thereafter, the. lapped. plates 1:. are. joined together baboltszzla and: the trough. bolts: 3. are. inserted; in. aligned hol eain. the. trough plates I; and the'lapped portiona-ois'the tank bottom. plates. is, with gaskets. d positional under the. heads of saidibolts: nuts of the bolts 3: are then tightened, so; a'sto scal thc top edges or the side wall: portions or the. troughs to the underside oi? the: tank bottom. After the: entiretank bottom is thus. laid, cement or other suitable sealing material a is; laitli along: theseams or joints of the tank bottom plates a: and around the bottom or the nuts 3 Subsequently, the trough systemis cut off" fromthe atmosphere, and a vacuum is pulled'on the-troughs; whereupon the sealingmaterial a is sucked in between the. lapped portions or the tank bottom plates whereit will set an hour or-so. Afiter the scaling material has: set, water pressure can be applied; to the scams or joints of the tankbottom by filling the elevated reservoir 3 with water; the vent pipe d. permitti ngair to escape from the trough system as the water flows through the troughs A. If

there are any leaks in the scams or joints of the tank bottom, they: can be easily detected by water escaping upwardly throughsamfi-Qnho the top side of the tank bottom.

Instead. of using water to test. thejseam's of the tank bottom, air under pressure: be. used as. the testing medium, In such instances. the valve 9 in the vent pipe 9 is closed and a pressure tank is substituted for the open tank 8 through which water was introduced into-the trough system. A reasonable pressure for such a test is 2-l-bs; 'to' 3 lbs. per square inch, butt-he troughs A maybe made to withstand desireclh lessure, even to the full head of liquid in the tank, in which case it forms; a double seal furthe tank bottom. Still another-method: of testing the tank bottom seams, would be to pull a very high vacuum on the troughs A when they are cut off from the atmosphere. This vacuum would tend to pull the bottom plates I of the troughs upwardly towards the tank bottom plates, and hence, would improve the tightness of the seal between the tank bottom and the side wall portions 2 of the troughs. Such a vacuum could be pulled while a sealing compound (for a bolted tank bottom) is applied to the seams of the bottom. The amount of vacuum could be controlled to just pull a semiliquid sealing cement between the tank bottom plates at the seams, as desired. A good way to make a sure and quick test for leaks in the tank bottom seams, is to flood the tank bottom with a few inches of water, and then apply about 1 lb. per square'inch air pressure to the troughs A. By any of the above described methods of testing, leaks in the tank bottom seams can be quickly and reliably detected during the operation of constructing the tank bottom, and accordingly, can be repaired before the tank is put in service. While I prefer to seal the side portions of the troughs A to the underside of the tank bottom, as above described, such scaling is not absolutely necessary, so far as detecting and recovering leakage is concerned, while the tank is in use. It is highly practicable to construct the troughs A from prefabricated members, such as steel channels I, properly interconnected with each other and simply laid beneath the tank bottom,

I 1' tothe underside of thecar due; toithez tact that. the weight. or thatch-ls bottom, plus the. weight: of? the liquid couilnflfi imthe. tank, would insure fairly tight. joints between. the. side portions 03? the troughs; the. underside or: the. tank bottom... Any leakage; would drain by. gran-ity through. the. troughsto: the peripheral edge of the tank bottom, where it. could be; detected ortrapped- If the-leakage, i-sgexcesslve thetank. couldi be taken out of service;

i and. the leaky joint; or joints repaired... In. the

case of" a. tank bottom. composed-L Ofz lapped. plates r5; joined together by welds 11.. as. shown Figures 8. and =93, no attemptis-made. to absolutely: seal theiside. walls or side. portions; oi. the-trou hs: bottom. suclr'a. tank bottom thetroughs: or trough sections; may be; formed from; pieces oi; channei iron tg-ar v ranged so that the top. edge. one. leg of the. channel. bears; against the: bottom face or the lower tank: bottom plate, and the other leg. of the. channel projects. upwardly along the. edge: of said lower plate. Before. the. top. plate. is. laid; onthe lower plate, the right hand leg. of channel (looking at Figure 8.) issecured; by tack welds l5.to.the edge or" said lower plate, as shownin. Figure '9. Thereafter, when the. top. plate is. laid or arranged in overlapping: relation with the; lower plate, said upper plate bears hard; against.- the; tacked leg of the channel, because: said leg; projects slightly above the top surface; or the lower plate. This. action of. the top. plate acts as. a. lever to. press the untackeds leg of; thechannel: Cleft. hand leg); tightly against. the; underside. of. the: lower plate, thereby insuring that: the channels. willv be. maintained in sufiiciently tight; engagement with the tank; bottom to-convey: leakage, to. the inspection on collection point or points at: the; peripheral: edge or the tank bottom- Whenatank is first. and: is: under watertest; (tanks. are practically always filled; with: water to. catch leaks in the side walls), troughs of the: kindaboue described; will definitely show whether the; tank bottom lacking; and approximately: the location of any leaks.

Prior to my invention it was the general custom to erect a tank bottom on horses about 2 /2 feet from the ground, and then confine about 6 inches of water on the top side of the bottom, and then crawl underneath the bottom and inspect the scams or joints in same for leaks. Another method employed for leak-testing welded tank bottoms, involved constructing an earthen dam around the outside of the tank, filling the same with water, and then checking the leaks from the inside of the tank. Such a method of testingfor leaks, is very unsatisfactory, especially in sandy soil, and in addition, the hydrostatic head obtained, is of the order of 2 or 3 inches which will not show all of the leaks that will occur at high pressure. Still another method of testing for leaks in a tank whose side wall is erected on an annular base of concrete, involved sealing the edge of the tank to the concrete and applying air pressure under the bottom of the tank. This allows only 2 or 3 inches H2O head, and necessitates soaping all of the scams or joints in the tank bottom, preparatory to looking for leaks. The above described methods of testing for leaks have not proved entirely satisfactory, on account of the liability of distorting the tank bottom plates; on account of the inability of being able to use a relatively high pressure in the testing operation; on account of the necessity of having to construct the tank bottom on elevated sup ports; and on account of the impossibility of quickly and accurately locating a leak that de velops after the tank has been put into service. My invention efiectively overcomes the inherent objections of prior methods employed for detecting .leaks in tank bottoms; it'eliminates the human equation in testing a tank bottom for leaks; it shows up weak or doubtful seams or joints because of the high pressure employed in the testing operation; it overcomes the necessity ofshifting or moving the tank bottom, after it has been fabricated, thereby eliminating the possibility of distorting the tank bottom plates; and it eliminates the possibility of the tank bottom plates being flexed upwardly and distorted during the operation of applying the testing medium to the joints or seams of the tank bottom; In addition to the desirable features just mentioned, my invention makes it possible to discover a leak at any time during the life of the tank, and Without the necessity of emptying the tank and going inside of same and inspecting the joints by eye, which is never perfectly reliable. My improved tank bottom can be reliably tested for leaks, even though the tank contains four of five feet of liquid, simply by applying air pressure to the troughs A, whereupon, in case there is a defective seam, bubbles Will rise through the liquid in the tank and make a sufricient noise to enable the approximate location of the leak to be determined.

My improved tank bottom is the only one, to my knowledge, thatwill definitely tell whether there are leaks in same at the time of construction, and also enable a small leak in the bottom to be quickly detected when the tank is in use. With tank bottoms of conventional construction, the only way tov discover a bottom leak, is for the leak to saturate the ground and show outside the tank. Moreover, thereis no way to collect the leakage and keep the tank in service, in instances where it would cause a great loss or inconvenience to empty the tank. My invention enables a leak to be detected before a large amount of material has leaked out of the tank, and it enables a leaky tankto be kept in service by collecting the leakage from the drain pipes 5.

I have herein illustrated my invention embodied in a tank erected on the surface of the 7 ground .and provided with a substantially flat bottom, that slopes either towards the center, or towards theside wall of the tank, but I wish it to be understood that my invention is applicable to tanks that are buried in. the ground, and also tanks provided with curved bottoms. In the case. of a buried tank, a vertical shaft would be provided for inspection of leaks.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

A tank provided with an upright side wall, a bottom composed of metal plates joined together, interconnected troughs, laid on the ground under said bottom in alignment with the seams of the bottom and having side walls that comprise resilient portions which bear against the underside of the bottom, said troughs leading to inspection stations located adjacent the lower end of the tank side wall on the exterior of the tank, and means accessible from the top side of r the tank bottom for attaching the troughs to said bottom. 7

' JOHN H. WIGGINS.

REFERENCES CITED The following references are file of this patent: V

UNITED STATES PATENTS of record in the Number Name Date 1,954,581 Wortmann Apr. 10, l34= 1,966.244 Hansen n July 10. 1934 2,126,997 Kramer Aug. 16, 1938 FOREIGN PATENTS Number Country Date Italy Jan. 14, 1931 

